Train-control system



7 Sheets-Sheet 1 Feb. 10, 1931. A. G. WILLIAMSON TRAIN CONTROL SYSTEMOriginal Fil-ed March 5, 1927 Swuemtoz m fmzm Feb. 10, 1931. A, G.WILLIAMSON 1,791,789

TRAIN CONTROL SYSTEM Original Filed March 3, 1927 7 Sheets-Sheet 2 Feb.10, 1931. A. G. WILLIAMSON TRAIN CONTROL SYSTEM Original Filed March 3,1927 7 Sheets-Sheet 3 A q Q a g M W QKJ M u new \km LEU may SW a L Q g@N Q m A w n m g QN m T avwemto'c Feb. 10, 1931. A, G. WILLIAMSON TRAINCONTROL SYSTEM Original Filed March 3, 1927 7 Sheets-Sheet 4 Z'II Feb.10, 1931. A. G. WILLIAMSON TRAIN CONTROL SYSTEM 7 Sheets-Sheet 5Original Filed March 3, 1927 vwentoz m $51 A (l-Horne Feb. 10, 1931. A.e. WILLIAMSON I 5 TRAIN CONTROL SYSTEM- Original Filed March 5, 1927 7Sheets-Sheet 6 Ell 351 flbtemug %%cP/=A Feb. 10, 1931. G. WILLIAMSON I1,791,780

I TRAIN CONTROL SYSTEM Original Filed March 3, 1927 7 Sheets-Sheet '7 iA N ambgutoz $3M A4 flue Mung Patented Feb. 10, 1931 1 UNITED ,sTArEsPATENT QQ H 1 AIRBAG. WILLIAMSON, or CARNEGIE, PL NNsYLvANIA, AssrGNon',isY MEsNEAssIGm MENTS, TO THE UNION, environ? &, SIG AL COMPANY, or

p TRAIN-CONTROL SY Application filed March 3; 1927, Serial No 172,325..Renewed November 19,1929. 1'

This inventionrelates-generally to train control and track Way circuitsystems, and has for its main object and feature the pro-- vision ofsimple means whereby at leastthree indications may be transmitted fromtrackway elements, preferably thetraffic rails, fed by a powersourceSuppl ing a singlefrequency current. I V

In the accompanying drawings the invention'is shown in "severalconcreteand preferred forms in which:

Fig. 1 is a diagrammatic view of a track circuit embodying one form ofthe invention.

Fig. .2 is a diagrammatic view of-one form of the train carriedapparatus, showing the use of rectifying detectors.

Fig. 3 is a view similar to Fig. 2 showing the use ofamplifiers. .j Fig.4 is a diagrammatic View showing a second form of track'apparatus. Fig.5 is a 'diagrammaticview showing a modifiedform of the invention'ofFigs. 1 and 4. :1 r r Fig. 6 is.- a diagrammatic view showing a stillfurther modified" form of the invention in which two track circuits areemployed.-

Fig. 7 shows a diagrammatic view of both train and track equipment of amodified form of the invention. 1

Figs-8 and 9 are diagrammatic views show-. ing the, difierent pronouncedharmonic components of a non-sinusoidal alternating cur-' rent. p a Fig.10 is a diagrammatic view of a magnetiz ation curve showing a thesaturation point. V

Fig. 11 1s a diagrammatic view showing a modification of theconstruction disclosed in frequencyalternating current can be madenon-sinusoidal; that is: the-alternating curswrss'v-ALn rENNsy q VANI Aconrona'rronor PENNSYLVANIA V l rent can be so modifiedfthat. themomentary values of a compound resultant wave do not vary in accordancewith a pure sine law, but. 1,

has momentary valueswhich are. the summa tion of the sine functions 'ofthe waves of several components. The sine function possessing the lowestfrequency is 'calledthefirst harmonic component'or the fundamentahandall the other sine functions, whose frequencies are multiplesof that of.the fundamental, are

called-higher or upper harmonic components. This is illustrated in thediagram, "Fig; 8 which shows one. cycle of asingler-frequencyalternating current-wave in 'whiclr'the horizontal axis represents timeand the vertical is the summation of the amplitudes of the severalharmonic components.

The harmonic components shown in Fig. 8 ar'ethe'first, or

fundamental, the third and the seventh, and it will be understood thatone or more such pronounced harmonic components may be utilized, byproperly tuning pick-up circuits on the train, to give variousindications. on the train to control suitable indicating means such assignals. or brake'setting means or both. a Y j A track way arrangementembodying the invention in one form is-shown in Fig. 1 in which thetrack elements are traffic rails 1 and 2 over which traflic moves in thedirection of'the arrow, said rails being preferably arranged in blocksA, B and G by means of insulated joints 3 orotherwise. Referringparticularly to block 13, a power source to supply a single frequencycurrent is shown and this may begenerator G which, in that event, couldbe connected directly by suitable leads to "rails 1 and 2 of each block,but, preferably, generator .G supplies powerto line wires 12 and 13 andthey in turn deliver current to the railsby means of transformer V T?)which supply the rails directly. The point that we are making is thateither generator G or transformer T6 may be considered the power source.Transformer Tb is here of the type having a closed ironcore so that byproper designing of the iron magnetic path the working point of themagnetization curve will be at the 'point X, Fig. 10, in consequence ofwhich secondary 4 becomes a source of alternating voltage supplyingalternating current of non-sinusoidal form and having pronouncedharmonic com- 7 pon'ents. A probable explanation of this phenomenon isthat there is a lack of uniforniity of the magnetic field of the ironcon stituting the magnetic path of generators and transformers, and thisis illustrated in Fig. 10 which showsga typ cal magnetization curve foriron. Let us suppose that the magnetiza tion ofthe iron has been broughttopoint X. If now, by means of anadditional alternating magnetizationforce, equal increments and decrements be added, tlie'inagnetizationwill increase duringt'ne positive half of the cycle bythe small amountef, while, during the negativehalf of the cycle magnetic induction willdecrease by a considerably larger amount 00+(Z. Such an asymmetricalcondition gives rise to pronounced higher harmonic components, the thirdharmonic component being particularly prominent.

Referring to Fig. 1, one'side of secondary l 18 connected to raill bywire 5, and rail 2 is connected to the o'pposite terminal of sec- 7 .endof block B in Fig. 1;tr ack relay Rb is con nected to the rails by wires16"and 17/ It will now be seen that normally, current flows fromsecondary 4- along, let ussay, WllG 5,

rail 1, wire 16, coil of relay Rb, wire 17, rail 2, wire 6, ohmicresistance 7, wire '8, front contact 9'and wire 10 and back to secondary4. If relay Ra is deenergized the return from rail 2 willbe over wire 6,impedance coil 11,

back contact 15, wire 10 and secondary 4.. The track relay, such as Rb,is an alternating current relay of the type that does not depend for itsoperation upon any particular'wave form of alternating current and willtherefore function in the same way whether-ohmic resistance"? orimpedance coil 11 is in the circuit; provided, of course that the valuesof 7 and 11 are such thatthe mean effective value of the current flowingin Rb is the same with either 7 orll in circuit.

The efliect,upon the current flowing in the rails, by cutting? and 11 inand out is as follows: When ohinicresistance'7 is in circuit, and theload on secondary 4 is largely noninductive, then current flowing in therails willhave' a pronounced third harmonic component in additionto apronounced first har 'monic component (or fundamental) that is,

ponent thereby leaving but a singlepronounced harmonic component, inthis instance the'funda-mental, and the wave curve will then besubstantially as shown in Fig. 9.

The probable explanation of this phenomenon isas follows: There-is botha voltage curve and a current curve and if the circuit contains onlyohmic resistance the current curve will havesubstantially the same shapeas the voltage curve. On the other hand, if the circuit contains largelyinductive, resistance the current curve will approximate moreclosely-apure sine wave than .will the voltage curve, this being due tothe fact that inductive reactance is proportional tofre quency and thusgreater in value for the higher harmonic components and it thereforetends to suppress 'the'higher harmonic components of the resultant wavemorefthan it tends to suppress the fundamental or first harmoniccomponent. Again, should the circuit contain capacity, then the higherharmonic components may be more prominent in the current curve than inthe voltage curve. It will therefore be understood. that resistanceelement 7 isnot anecessary part of the invention. It is placed inthedrawing largely to illustrate thecharacter ofthe-circuit. it does,however, possess areal function in preventing the current from beingdissipated when impedance coil 11 is not in circuit".

In th'e illus trative form of the invention described thus far it willbe understood that allthe blocks of the system are equipped in themanner described in connection with block The track way arrangement, inthe present form, is therefore that when block A isunoccupied.aiid'relay Ra is'energized a non-sinusoidal single-frequencyalternating current will fiow in the rails of-block B and this currentwill be characterized by two pronounced harmonic components, here thefirst and-the third components.- Vlien block A is occupied and relay R0;is deenergized then the current in the rails of block B will have asingle pronounced harmonic component, here the fundamental, and a verysmall, if any, third hamonic component. If a second train enters a blockalready occupied then such second train will receive no current, due tothe shunting action of the wheels and axles of the trainin advance.- ethus establish three traffic cond-itions with a single alternatingcurrent, a great simplification over systems now used. The track wayarrangement shown has another advantage in that it is not necessary tohave a separate trackcircuit to energize the track relay, this functionbeing performed-by the same cur:

rent as that which energizes the means on the train. It will also beunderstood that, wayside signals of the three position type can beoperated and controlled by a track way circuit of this type by havingtwo track relays, one responsive to one pronounced liar-avoltage'induced' in them by current Iiowingv in opposite directions inthe trafiic rails will be additive, and are further connected in acircuit including wires 22, 23, 25 and 2,. as well as primaries 24 and26 of transformers T and'T. Said transformers are alike and are of thetype commonly used in this class of work, their primary windings having,a

high impedance. E and E represent two rectifying detectors of theelectron tube type containing here three elements, a filament,

a grid and aplate. The grid circuit of tube V E is as follows: secondary28 of transformer T, wire 29, condenser 18, wire 19, grid 32, filament33, :wire .34 and back to secondary 28. Tuning condenser 35 bridges thiscircuit by means of wires 36 and 37, and, in this instance, condenser 35is so chosen that the cir cuit is tunedto resonance with the fundamentalor first pronounced harmonic component of thetiackcircuit current.Thegrid circuit oftube E is as follows: seconaryr38 of transformer- T,wire 39, condenser 40, wire 41, grid 42, filament 43, wire 44 and backto secondary 38. Tuning condenser 45 bridges the circuit by means'ofwires 46 and 47, and, in this instance, condenser 45 is so chosen thatthe circuit ist-unedto resonance withthe third pronounced harmoniccomponent of the track circuit current.

Generator G, of the train equipment, is driven by any suitable means,such as a steam turbine, not shown, and delivers a voltage that drivesmotor M of motor generator MG. Thegenerator end of the motor generatoris supplied with two commutators G and G the former furnishing a voltagesuitable for the filament circuit of E andE, and the latter a'voltagesuitable for the plate circuits of tubes E and E. The filament cir- 52,plate 1530f tube E, filament 33 andwires 50. and 54 back to commutator G1 The plate circuit of tube E consists of: commutator G wires 51'and 55,coil OfreIayR, wire 56, plate 57 of tube E, filament 43, wires 44, 49and 34,-filament 33 of t-ubeE, and wires 50 and 54 back to'G By theforegoing means the grid circuit of tube E is responsive to theinfluence of another pronounced harmonic component of the track waycurrent.

The effect of each of these pronounced harmonic components is to renderthe grid, complementary thereto, negativefwith respect to the filment solong as the appropriatecurrent flows in the track way. If the originalvalue grid circuit of tube E isresponsiveto thQzlIlfiLlBIlCBOfOIlGpronounced harmonic component and the of the plate circuit current isassumed to be 1.00 when no curr-entis flowing in tliegi id' circuit,then, whentlie grid-is rendered negative by the induced voltage in thegrid'circ'uit, the plate circuit current is choked downto'say 0.40 afterthe manner describedin detail in application Ser. No.147,403,filedNovember 10,1926; that is, anintermediate value of plate circuitcurrent is established so long as the appropriate 7 current flow ispresent in the ralls. 2

Relays R and 'R arealike'landare lier'e of the direct current polarizedtype. Each 7 relay is provided with a single polarized'armature which isso biased by air gap adjust-;

merits and strengthof magnetic poles that i it will take one position"(right hand posiflowing in the coils of the relay, butyif the currentvalue of the plate circuit is either increased or decreased or failstotally, then the polarizedarinature will be forced to anothe)rposition'(in Fig. 2the left'hand positlOIl I 1 i l The indicating. meansused may be of any suitable character and may be merely an indicatorsuch as I having three difi'erentlycolored lights and these lightsreceive, in this instance, power direct from generator G"; The proceedindication light-circuit is as follows: generator G, wires 58 and 59,armature 30 of relay R, contact point 31, connection 60, armature 66 ofrelay R, contact point 61, wire 62, li 'ht 63 and wires 64 and 65 backto generator G. The caution light circuit is as follows: generator G,wires 58 and 59, armature 30, contact point 31, connection60,

armature 66, contact point 67, wire 68, light 72, 64 and 65 back togenera:

-1o0 tion 2) when current of the proper 5 I polarity and of a givenvalue(here"0.40) is 1 unoccupied, thenthe wheels and axles of the train willshunt the" current from track rielay Rb, and, the track cir'cuit'currentfor block B there'being only ohmic resistance in said circuit(graphically indicated by element 7 will have two pronounced harmoniccomponents, and this current will be picked .up by coils and 21. Each ofthe grid circuits oftubes E and E will respond to its proper pronouncedharmonic component and the grids of both tubes will be rendered negativewith the result that the plate circuit current of each tube willbechoked down to an intermediate value of say 0.40 and'consequentlyarmatures and 66 will both occupy the righthand' position shown in Fig.2. This will close the proceed indication circuitpreviously described.It block A were occupied when the train entered block B then track relayRa would be deenergized and the current supplied to the track railswould pass through impedance coil 11' and this would eliminate, or atleast greatly minimize or render ineifective, the third pronouncedharmonic component and therefore the grid of tube E would no longerremain negative. Consequently the value of the current in the platecircuit would rise to 1.00, armature 66 would move totheleft handposition and the circuits would rise to 1.00 and both arma tures 30 and66 would be moved to the left hand positions with the resultthat thecircuit previously described through danger light 71 would beestablished. It will also be understood that should a wire break ineither of the plate circuits or the source of power fail then eitheror-bot-h armatures 30 and 66 would move to the left hand position.

The train-carried apparatus can of course be made as elaborate asdesired and may in clude bothbrake setting means and multiple speedcontrol means in accordance with the requirements of the system on whichit is used. In Fig. 2 there happens to be shown, in addition toindicator 1, brake setting means designated by three magnet valves M, M

. and M, the coils of which are connected'in parallel respectively withthe proceed, caution and danger indicationlights. The circuit tor valveM branches off wire 62, and then passes over wire 73, coil of M, andwire 74 back to wire 65. The circuit for valve M branches ofi wire 68and then passes over wire 75, coil of M and by wire 7 6 back to wire 65.The circuit for M branches oil wire and then passes over wire77, coil ofM", Wire 78 and back to Wire 65. In Fig. 12'is shown a detail view ofthe valve structure, which, however, may be varied widely. BV indicatesa brake valve which in its normal position has port 131 closed and port125 open. Under these circumstances, pressure can flow from. the brakepipe to the engineers valve but cannot flow to exhaust port131'. The

brake valve ismaintained in this position by pressure under piston 130but when this pressi'u'efa ls port 1251s'closed and port 131'is openedthereby connecting the brake'pipe with exhaust port 131- Pressure ismain-v tained under piston 130 by the three magnet valves M, M and h thevalve ports of which i are connected-in series with each other, and areconnected at one end with the cylinder containing piston 180 and at theother end with an :ghaust 131". WVhen valve M is energized port 126isclosed'and valve 124 '131" and ports 131 and 131 will be open and port125 will be closed, thereby applying the brakes. Each ofthe magnetvalves is so constructed that when it becomes deenergized its armaturesuch as 1 23, 128 or 128 falls so far down that it will not be: liftedwhen the magnet is reenergized. The engineer should thereforeacknowledge each indication by lifting a plunger such as 122, 129 or 129manually to thereby restore the armature;

. In Fig. 3 is showna second embodiment of the invention in whichelectron tubes E and E: are used as amplifiers and relay's R and R arealternating current relays. In this formot the invention two pairs ofpickup coils are used, 80 and 81 being-connected to the grid-filamentcircuit of tube E and coils 83 and 8 1 being connected to the gridfilament circuit of tube E. Condensers 82 and 85 span the respectivegrid-filament circuits to tune the two circuits to resonance of the twopronounced harmonic components. In this instance the grids of the tubesare not rendered negative but an alternating component is impressed uponeach plate circuit and eachrelay R and R responds to the influence ofthe proper pronouncedharmonic component in the track circuit. The trackcircuit shown in Fig. 1 can be used-in connection with this trainequipment, and the general method of operation will be the same as thatpreviously described in connection with Figs. l and 2.

In Fig. 4 is shown a modified form'of track circuit construction inwhich, when the track relay of the block in advance is energized, ashunt path 1s;closedgaroundimpedance coil 3 8t and which shunt pathincludes the con;-

I ing'thepositivelhali of the cycle ofithe alterdenser 87. Thiscondenser is given such value that it counteracts {theinductivereaetance of coil '86 so, that the apparent rcsistance otter-edto the track circuit current is thatof ohmic resistance. Under theseconditionsth'e track current will have two pronounced larnioniccomponents, the first and the third. lVhenthe track relay ofjtheblock injadvance is'deenergized then impedance coil 8(lis placed 7 incircuit and the third harmonic component ofthe track current will besuppressed; The construction shown in F1g. 4: can be associated with theconstruction shown in either Fig. 2 or 3. w

nating current the induction' will increase but slightly while duringthe negative halfof the cycle the decrease will 1 be relatively large.

7 This uneven change in the induction otthe iron core willproduce a Waveform in the current of the secondary l of transformer Tb which will havea pronounced third harmonic component as well as a pronouncedfirst-harmonic component. .lVhen'relay-R is deenergized and coil 250thereby also becomes de'energized then the working .point on themagnetization curve is well down belowthe knee otthe curve and thepronounced third harmonic componentis suppressed. The result isthereforethe same as inlFigs. '1. and .4.

In Fig. G is shown stillanother modification of the invention inwhichtwoztrack circuits are; used As there shown, secondary 4 oftransformer T?) is connected, at the outgoing end oftheblock, to'rails 1and 2 to which latter, at the incoming end of the bloclgis connectecltheusual track relay, therails being in series; Inasmuch as this circuitcontains merely ohmic resistance the'currentflow in the rails willhave,let us' say, a pronounced third harmonic component. 200 indicatesanother secondary oftransfo'rmer Tb which supplies power to a circuitasfollowsz wire 201, contact 202, armature 203 of the'track re lay ofthe block in advance, Wire 1204, center tap205,rra'ils1 and 2 inparallel, centertap' 206 wire207 and backt o secondary 200.7 51nasniuchasfthea resistance of thisj-rcircuit is" V 1 largely; noneinductive} theLcurrent". flowing therein; will :h'avef. pronounced. higher,moniecomponents Sletfusi say" notably; the

' fthirdzharmonic component; Pick-up: coils 2l0and211 for train212iareso-conne'cted that difi'erent 'tiiaiiic the voltage induced inthem by the current supplied by'secondary 4 to the rails in series willbe additive, and the pick-up circuit is tuned to resonance at thefrequency of the third; harmonic component. This pick-up circuit isconnected to the grid circuit of tube 2) inthelsame manner'as'inthatfig- '2 in, the way previously described." I: Pick-up coils 213 and21 loftrain-2l2 are so connected that voltage induced-therein byvcurrent fiow ingin' parallel in-the rails will be additive, and thepick-11p circuit is tuned to resonance at the frequency of the thirdharmonic comcs0 .ureand wilitheretore control relay R. of Fig.) 7 irelay "of the block in advance is deenergized advantage of, thisparticular form of the inyention, in which hothpick-up circuits areresponslve to higher harmonic components is that this system is notsubjecttothe influence of stray currents. z. H

The, systemisnot' limited to three indications; Obviously twoindications, or even one indication can be used as will beapparentirom'Fig. 6; So also a number of indications'greater than threecan be employed, since this may be desirablewhen short blocks are. usedandthe-speed of certain'i'classesof trains'ishigh, 7 T

i In Fig. 'Z a system having lmore-than three indications is shown; Whenfour indications aredesired-an'additional tubeE is employedvand also anadditional coordinating relay- R with the necessary grid, plate andfilament circuits; However, ea s this additional.;eqi iipmentiis largelya repetition, of

what has been descrihed in connection ith i tubes "E and'ET it-isthought, to be unneces-J 'saryatoi repeat the description thereof; In

Fig.7 we have chosen to use the tubes as recernor geared 't o-the train.Four'segments arev employed j227, 228, 229 Land 230 withfjwhic'h"thecontact arme-ngagesand thesep seg'- V nientslareaofdilierentflengths tothe-reby in itson the train underposegdilierentspeedli ,onsi-n a manner I well 'tifying 'detectorsgbutxitwill be un'derstood from Fig. 3 that thetubes 1may be used asamplifiers. In-Fig. -7 the indicating means understood. The trackcircuit arrangement shown in Fig. 7 is a modification of that shown inFig. 6 in that a line relay 215 is employed at each block togetherwit-ha controlling circuit for this relay 215. Associated I Withtransformer Tb is a secondary 21 6 con' nected in a circult as follows:w1re'2l7, ar-

mature 218 of the track relay of block A, contact point 219, wire 220,coil of relay 2150f block B and then by a common return wire indicatedat back to secondary 216.- That track circuit of block C which includesthe two rails in parallel is then controlled through a contact of linerelay'215 in such a way that when relay 215 is'energized then theparallel track circuit passes throughnon-inductive resistance 221 andfront contact 222, whereas when relay 215 is d'eener'gized then saidparallel circuit includes inductive react ance'22l-and-back contact 223f Therefore each block'is provided with a series-rail circuit currenthaving a plurality of pro- 40 c r train entersthe block C, then thesecond train nounced harmonic components, here the first and third, andwith a parallel-rail circuit current also having a plurality ofpronounced harmonicicomponents, here the first and third, and it will beunderstood that this is will receivef no'current at all. -The'pickuipcoils on thetrain associated with tubeE are 'connected to respond to theseriesfrail cur rent, and the pick-up circuit associated therewith istuned to proper resonance atthe frequency of'one of the harmoniccomponents of this current-preferably the I higher .h-armonic component.=The'other pair of'coils in the train is connected to responda'to theparallel-rail current and the grid circuitof tube E' is tuned toresonance; at the frequ'ency of the first harmonic component while-thegrid circuitoftube E is tuned to resonance withthe third' harmoniccomponent of said parallel-rail circuit current;- Therefore, when atrain enters a block, andthe-neXt two blocks in advance are unoccupiedall: three tubes E, E and' E; are influenced and relays R, -R" andqRTwill hold;theirfarmaturesein the rig-lit hand positions and; themaximum1 speedwilhbe permittedQ Ifthe second 'block in advance is occupiedandithe' first block in advance is unoccupied then tubes E" and E;

are-"influenced a'n'd 'relays Rfiand Rf will; holtl their armatures inthe right hand positions, but tube IE will not be influenced and relayR" will hold its armature inthe left hand position thus permitting thetrain to proceed at the second speed. If the first block in advance isoccupied then tube E only is influenced and only relay R will hold itsarmature in the right hand position, the armatures of relays R and Rbeing in the left hand positions, thus permitting the train to proceedat a still lower speed. Ifthe block is already occupied when the secondtrain enters then.

all three relays R, R and R will move their armatures to the'left handpositions and the train can proceed only .at the lowest speed.

In Fig.11 shown a modification of the form of the invention shown inFig. 7.. Here each block is provided with a two-element A. C. polarizedrelay such as Ra so constructed that when ablock is supplied withcurrent of one relative polarity from a secondary such as ethecorresponding track relay will hold armatures 252, 253 and 254 in theright hand positions, will hold said armaturesinthe left hand positionsif'current of reverse relative polarityisapplied,arid when a track relayis deene'rgized the correspondingarmatures will occupy-themid-positions; Each track transformer, of which Tb is an example, is

provided with a se'condary 255 that supplies.

power to the local element'of the correspond mg track relayyandassociated with each transformer is a coil 250 to increase the"magnetization of the iron core of the transformer to near thesaturation point so that, whenever coil250 is energized by battery 251,the current delivere d'by secondary 4' will have .pronouncedhigher'harmonic components. The circuitfor 'coil250 and battery 251passes through the rightand left hand contacts of the track'relay Ra,and said coil 250-will thereforebe energized whenever thetrack windingof a relay, as Ra, is energizedfregardless of the relative polarity ofthe energizing current. Each'block; is provided with two filters 256 and2.57, filter25i6jbeing composed 'ofi nductance 2'58 and capacity 259arranged in parallel, and the. values; of. those elements are so chosenthatthe filter is resonant to the seventh harn onic'component; ofcurrentsup.-

p'lied bysecondary 1 and will'readily pass; it while the other harmoniccomponents; except the first, will" be suppressed. Filter- 257 iscomposed ofinduotance 260 and capacity-261 in parallel and their valuesare so ohosenthat it is-zre'sonantv to the" third harmonic? com".-ponent of current delivcred byfsecoiidary' 4 and wiill i readily pass;it- While theother liar..- monic- ;components, except the first, will beits suppressed: t When, therefore,, ther armatures, 0f: r iayna occupythe? right-hand. positions 1a current will; flow infthe" rails having}two pronounced harmonic components, here the l first "and seventh; andwhen; said? armatures occupy the left hand positions acurrent will flowin the rails having two pronounced haremonic components, here thefirstand third. hen the armatures occupy the mid-positions the currentin the-rails ill have only the first harmonic component.'Tll6S'3,Yl3l11.6

conditioifis correspond to-three ditl'erenttralifit: conditions,thefourth being totalabs'enceof current 'WlllCh condition prevailswhen'a a I block 13 already occupied by a train when the second trainenters. *On the train, the grid circuit of tube E is tuned to the firstharmonic COlHp0l16I1t,' l l1 grid circuit of-tube SE. is tuned to thethird harmonic component and the grid circuit of tube E istuned to theseventh harmonic component. Relays R, R and-R are each providedwithtwopolarized armatur'es in place o'f one showniinother forms of theinventioi'l. l Vhen tubes E and E are influenced andtubc 'E isuninfiuenced, (two blocks in advanceunoccupied) then thefmaxim uin speedis permitted; with tubesE and E influenced and tube E" uns influenced(second block in advance oc cupied) 'then the second speed is permitted;

- flow, means in said connectionstor' establisha given pronouncedharmonic componentsand. othermeans 1n said connections 'to determine wayelements,'a current now, means in said ing ware -form, for saidjcurrent,-having if said given harmonic components 7 are; re-

tained in thewaye form ctthe-current'flowing in thetrackwayelements orit; saidgiven harmoniccomponents are suppressed.

A' trackwa-y ci'rcu'it syst'em including-t 'trackway elements dividedinto blocks, a

power source to supply n elements ofa block to establisln in' saidtrack- 'connections to establish awave form for said current hav nggiven pronounced harmonic components, othermeans lllSLlCl connections tod termine itsaidgiyen' harmonic components are retained in the -wa-veformofthe' currentflowing in the'trackway elements of a. block, Orifsaidg ven harmonic components are supe pressed, :and a tra 'trol' theconnections aforesaid." 1

,sin'gle alternating {current-of a"g1ve11 frequency, con-nectlonsbetween said power source and the trackway slatin'g device {responsive IA tracliwaycircuit system; ncluding'ti trackway' elementsa powensource'tosupply a singleialternating current of a given fre: quency, saidcurrent having a pluralityof pronounced components, and trafliccontrolled Variable connectionsbetween the source and the tra'ckwayelementsito selectively re tain or suppress one-or. moreof; saidcornponents :to thereby establish in the, trackwa elements a currenthaving-in response to di zterent traflic conditions all or less than allof said components,v Y

s. A 'tra'ckway trackwa'y elements arrangedfiin blocks, a

circuit system 1 a including )OWGl'JSOlllCfi tosu) l alsin'le'alternatin f current of a given, frequency, said current haying aplurality of. pronounced;compon'ents, variable connectionsbetween thesource and the trackway element's of'a block tosel'ectivelyxretainvorsuppress one orv more of said componentsto thereby establish inthe.tralckway elements of a block acuri'enthaving'al'l or less than all ofsaid components, and a translating device,- respons ve-to trafficconditions of'another block, tocontrol. the] Variable connections. I

v 5. A Ytrackway circuit system' including 1 trackway elements arrangedin blocks; a

power source to'supply a single alternating current of. agivenxfrequency,said current having a. plurality offpronouncedu compo?nents,yariable connections between the source and the trackway. elements:of a ;-bloc'k to sele'ctively retain-or suppress one .or more of saidcomponents to thereby-establish inthe -trackway elements of a block acurrent hay:-

ing all or less than all of said components, and a 'translat ngdevice,responslveto the presence oficurrent flowhaving one or more pronouncedcomponents in the trackway' elements of another block, to control theVariahle connections. L

,6. A trackway circuit system including: a

--trackcomposed of "traffic-' rails, 1 a; 'powe r source to supply asingle alternatingturrent of a given frequenc'y, said" currentlm'v ing:a 1

plurality of pronounced components, and

tralfic-controlledariable Qconnections- :be-

tween the source and the trailic rails to selectively retainer suppressone "oi "more of said components to thereby e'stablishjiirthetrafficrails. a. current haying in response to different traflic conditionsallor less than} all of said'coinponents. A trackway circuit trackcomposed'of traffic V x in blocks, a power source to supplya single a?components, va r'iable connections between Es -heisource and'thetraffic-rails of a block to selectively retain. or suppress one or saidcomponents to thereby establish 1n the system including z u 1 s an arnge rernating current of a giren frequency, said current having apluralty of pronounced traffi rails ofa block acurrent hayinglall'or less thanall of saidlcomponents, andatranslating device, resp'onslve'to;trafiic;cond1t 1on s of another block, to control the variableconnections. V

8. trackway circuit system including: a track composed of tra'fiic railsand arranged in blocks, a power source to supply a singlev alternatingcurrent ofa given frequency, said current having a plurality ofpronounced components," variable connections between the source and thetraflic rails of a block to selectivelyretain or suppress'one ormoreofsaid components tothereby establish in'the traffic rails ofj'a block avcurrent having all or less than all of'said components, and atranslating device, responsive to the presence of current flow havingone or more pronounced components in the traffic rails of another block,to control the variable connections.

' 9; A-train control system including: trackway elements, a power sourceto supply a single alternating current .of a given frequency, said'current having a plurality of pronounced. components,traffic-controlled variable connections between the source and thetrackway elements to selectively retain or suppress one or more of saidcomponents to therebyf establish in the trackway elementsa and-thetrackway' elements of -a block to se- 7 lectively, retain or; suppressone orVmo-re of saidcomponents to therebyestablish in thetrackwayelements of a block a current-having all o'r-less than allo-fnsaid components, a

' translating-device, responsive to traffic conditions of-another block,,to-control the; vari1- able connect ons, a vehicle, ind cating means onthe vehicle, and translating, means on the vehicle selectively,responsive to the influ ence of dliferent components ofthe currentinthe-trackway elements to thereby control tlieind'icatjing' "means-v togive different indications corresponding to different traflic' con- (lllIlQIlS,

111', tram control system includingf tr'ackway element's arranged inbloksja power; sourceto supply a single alternating current of 'a givenfrequency, said current having a plurality" of pronounced components,variable conrrectibnsa'gbetween the v sfmrraeiand the trackway elementsof avblocl:

to selectively retain or suppress one or? more said components.- to:thereby establish in mg'means to'give different indications corre-- thetrackway elements ofa block a current having all or lessthan all of saidcomponents, a translating device, responsive to the presence of currentflow. having one or more pronounced components 111 the trackway elementsof. another block, to control the variable connections, a vehicle,indicating means onthe vehicle, and translating means on the vehicleselectively responsive to the influence of diiferentfcomponents of thecurrent in the trackway elements to: thereby; control the indicatingmeans to give difierent indications corresponding to different trafficconditions.

12.:A train a control system including: a track composed; of trafficrails, a power source tosupply a-single alternating current of a givenfrequency, said current having a plurality of pronounced components, andtrafli-c-controlled variable connections between the source and thetraflic rails to selectively retain or suppress one-or more ofsaidcomponents-t0 thereby establish in the trafiic rails aicurrent havinginresponse-to difi'erent traffic conditions all or lessthan all of saidcomponents, 'a' vehicle, indicating means on the vehicle,- andtranslatingv means on; the vehicleuselectively responsive tothe.Iinfluence of different components: of thecurrent in the trafficrails to thereby control the 7 indicating means to give differentindications corresponding, to difierent ,traflic conditions. 7

13. A train control system including: a track composed of traflic rails:and; arranged inblocks,a power source to supply a single alternatingcurrent of a given frequency, said current having a plurality ofpronounced components, variable connections between the source and thetraffi'c rails ofa block to selectively retain or suppress one or,

more of said components to thereby establish inthe trafiic rails of. -ablock a current having all or less than all ofsaid c0mp.onent's,a.

translating device, responsive to traffic conditions ofanother block, tocontrol thevariable connections, a vehicle,indicating means on thevehicle, and translating means on the vehicle selectively responsive tothe influence.

of difierent components of the currentinthe tra'fiic rails to therebycontrol the indicating means to. give different'gindicationsgcorresponding to different traflicconditionslu 14. A traincontrol systemincluding gqa 'trackcomposed of'trafli'c rails and arranged in. blocks-,a power sourcezto. supply. a single alternating; current of. a given.frequency,

said 1 current having a plurality of pro nounced; components,varlableconnections between thegsource and-the trafiic rails of; a

block to selectively; retain or: suppress one or more of,saidcomponentstothereby estab 1 lish -in the traflic 'rails of ,a blockla current having all, I or less; than all. of saidv e comp-01 nents, a'translating-device,responsive to the presence-of, current-flow havingone. or more pronounced componentsinthe 'traific rails of anotherblock, to control the variable connections, a vehicle, indicating meanson the vehicle, and translating means on the vehicle selectivelyresponsive to the influence of different'components of the current inthe traf-' fic rails to thereb control the indicating means to give dierent indications corresponding to different traific conditions.

15. A train control system including; a track, a train, a single sourceof current, a

trackway current modifying means, alternative paths to connect thecurrent source to the track with the rails in series by Way of thecurrent modifying means or independently thereof, train-carried circuitmeans including two electron tubes one of which is responsive only tounmodified current and the other of which is responsive only to modifiedcurrent in said track, and trafiic-controlled means to connectone or theother of said paths to the track. 1 a

16. A train control system including: a track, a train, a single sourceof current, trackway means to modify the form of the current,alternative paths to connect the current source to the track with therails in series by way of the current modifying means or independentlythereof, train-carried circuitmeans including two electron tubes one ofwhich is responsive only to unmodified current and the other of which isresponsive only to modified current in said track, and rtraflic-controlled means to connect one or the other of saidpaths to thetrack.

Signed at New York city, in the county of New York, and State of NewYork this 14th day of February, 1927. r V r ABBA G. WILLIAMSON.

